Diabetes is associated with changes in vascular permeability and vasomotor control as well as with increased morbidity and mortality after surgical procedures. This is especially true after heart operations involving cardiopulmonary bypass (CPB). Recently, we have demonstrated that permeability-modulating proteins such as vascular endothelial growth factor /vascular permeability factor (VEGF/VPF) are increased in expression in diabetes and are associated with increased edema formation and length of hospital stay in diabetic patients. Since alterations in vasomotor regulation are critical aspects of morbidity of CPB, a better understanding of the regulation of the microvasculature of diabetic patients may lead to improved outcomes in diabetic patients. The goal of the proposed research is to determine the effect of well-controlled and poorly controlled diabetes mellitus on alterations in signal transduction associated with vascular function and to investigate the changes that occur in patients undergoing heart surgery. Specifically, we will determine the roles of tyrosyl kinase / phosphatase activities, protein tyrosyl phosphorylation, mitogen activated protein kinase (MAPK), and expression of inducible cyclooxygenase (COX-2) in mediating acute changes systemic microvascular reactivity and permeability during clinical cardiac surgery. Protein phosphorylation plays a critical role in numerous vascular processes including vasomotor regulation and the regulation of vascular permeability mediated through adherens junctions and other endothelial cell-cell contacts. In addition, agonist induced microvascular smooth muscle responses to serotonin, endothelin-1 and thromboxane A2 will be examined after cardioplegia in the coronary microcirculation in well controlled, poorly controlled diabetic patients and age-matched non- diabetic patients. Recently, poly(ADP-ribose) polymerase (PARP) has been demonstrated to cause endothelial dysfunction and other vascular injury in diabetic patients. Thus, we will examine the changes in nitrosative stress, PARP activation and apoptosis inducing factor (AIF) translocation after CPB in vessels obtained from diabetic patients, and age-matched non-diabetic patients. This work will be accomplished through an exhaustive approach using molecular and cellular biology techniques to examine the protein phosphorylation and gene expressions involved in maintaining vascular integrity in clinical cardiac surgery involving cardioplegia and CPB. Importantly, we will use cDNA microarray technology and standard molecular and cellular techniques to examine upregulated and downregulated genes and enzymes in diabetic patients and correlate the molecular and cellular changes with clinical outcomes and in vitro indices of vascular alterations. The results of these studies may have significant implications regarding the recovery of diabetic and other patients after cardiac surgery involving cardioplegia and CPB.